This is high quality natural PTFE Teflon tubing. Great for insulating and protecting bare wire/leads. Operating temps from 500°F down to -454°F. Internal diameter measures 0.020"-0.026" (0.51mm-0.66mm) with a wall thickness of 0.007"- 0.013" (0.18mm-0.33mm). Priced and sold by the foot (0.305 meter).